The option
element content is taken as plain text (no tags are recognized), so there is no direct way to do it. As a clumsy workaround, you can hand-format the options using a monospace font and use no-break spaces:
<style>
select, option { font-family: Consolas, monospace; }
</style>
<select>
<option>option 1 0.5
<option>option 2 1.5
<option>one more option 110.5
</select>
(where the spaces inside the option
elements are no-break spaces; use
for them if you don’t know how to type no-break spaces in your authoring environment).
A completely different workaround, or approach, is the replace the select
element by a set of checkboxes (or, depending on desired logic, radio buttons) and associated labels. You can then represent this data in a table and set suitable formatting on it:
<table>
<tr><td><input type=checkbox> <td>option 1 <td align=right>0.5
<tr><td><input type=checkbox> <td>option 2<td align=right>1.5
<tr><td><input type=checkbox> <td>one more option <td align=right>110.5
</table>